In-mold forming has been known as a process for producing, by integral molding, a molded resin article bearing a label bonded thereto. This process comprises attaching a label to the inner wall of a mold beforehand, melting a molding resin, e.g., a polyethylene resin or polypropylene resin, directly feeding the molten resin into the mold, and molding the resin by injection molding, blow molding, pressure-difference molding, foam molding, or the like and simultaneously bonding the label thereto (see, for example, patent document 1 and patent document 2). Known labels for use in such in-mold forming include resin films printed by gravure printing, synthetic papers printed by multicolor offset printing (see, for example, patent document 3 and patent document 4), and aluminum labels obtained by laminating high-pressure-process low-density polyethylene, ethylene/vinyl acetate copolymer, or the like to the back side of an aluminum foil and printing the front side of the foil by gravure printing.
In the process in which those labels for in-mold forming are used to produce decorated labeled molded articles by in-mold forming, the labels employing high-pressure-process low-density polyethylene as a heat-sealable-layer resin show tenacious satisfactory adhesion to the molded articles when the material of the molded articles is high-density polyethylene. However, these labels have had a drawback that when the molded articles are made of other materials such as, e.g., polypropylene and polystyrene, adhesion between the labels and the molded articles is low and the labels peel off the molded articles during transportation. For attaining tenacious label adhesion to molded articles, it is necessary that labels for respective molded articles should be prepared in which the heat-sealable layers are made of the same kinds of resins as the corresponding molded articles. This has posed a problem that label stock management is complicated. The following problem also has been pointed out. Since low molding temperatures in molded-article production result in an insufficient adhesion strength between each molded article and the label, it is necessary to set the molding temperature high in molded-article production. Consequently, molding temperatures in molded-article production are considerably limited, resulting in a decrease in productivity.
Furthermore, there has been a problem that in the case where a label is printed, e.g., by gravure printing to form dots on the surface of the printing layer, many ink transfer failures occur when the surface of the printing layer is too rough, resulting in a considerably impaired print appearance.    Patent Document 1: JP-A-58-069015    Patent Document 2: JP-A-01-125225    Patent Document 3: JP-B-02-007814    Patent Document 4: JP-A-02-084319